Sulforaphane suppresses TNF-alpha-mediated activation of NF-kappaB and induces apoptosis through activation of reactive oxygen species-dependent caspase-3.
Sulforaphane (SFN) is a biologically active compound extracted from cruciferous vegetables, and possessing potent anti-cancer and anti-inflammatory activities. Here, we show that tumor necrosis factor-alpha (TNF-alpha), in combination with a sub-toxic dose of SFN, significantly triggered apoptosis in TNF-alpha-resistant leukemia cells (THP-1, HL60, U937, and K562), which was associated with caspase activity and poly (ADP-ribose)-polymerase cleavage. We also report that SFN non-specifically inhibited TNF-alpha-induced NF-kappaB activation through the inhibition of IkappaBalpha phosphorylation, IkappaBalpha degradation, and p65 nuclear translocation. This inhibition correlated with the suppression of NF-kappaB-dependent genes involved in anti-apoptosis (IAP-1, IAP-2, XIAP, Bcl-2, and Bcl-xL), cell proliferation (c-Myc, COX-2, and cyclin D1), and metastasis (VEGF and MMP-9). These effects suggest that SFN inhibits TNF-alpha-induced NF-kappaB activation through the suppression of IkappaBalpha degradation, leading to reduced expression of NF-kappaB-regulated gene products. Combined treatment with SFN and TNF-alpha was also accompanied by the generation of reactive oxygen species (ROS). Pre-treatment with N-acetyl-l-cysteine significantly attenuated the combined treatment-induced ROS generation and caspase-3-dependent apoptosis, implying the involvement of ROS in this type of cell death. In conclusion, the results of the present study indicate that SFN suppresses TNF-alpha-induced NF-kappaB activity and induces apoptosis through activation of ROS-dependent caspase-3.
Moon
Dong-Oh
DO
Department of Marine Life Science, Cheju National University, Jeju 690-756, Republic of Korea.
Kim
Mun-Ock
MO
Kang
Sang-Hyuck
SH
Choi
Yung Hyun
YH
Kim
Gi-Young
GY
D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D024202:Electrophoretic Mobility Shift Assay; D004789:Enzyme Activation / Q000187:drug effects*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D017879:Isothiocyanates; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D009369:Neoplasms / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013454:Sulfoxides; D013861:Thiocyanates / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D016588:Anticarcinogenic Agents; D020672:I-kappa B Proteins; D017879:Isothiocyanates; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D017382:Reactive Oxygen Species; D013454:Sulfoxides; D013861:Thiocyanates; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D053148:Caspase 3; C016766:sulforaphane